Unusual high-origin of the pronator teres muscle from a Struthers' ligament coexisting with a variation of the musculocutaneous nerve.

During routine anatomical dissection of the right upper extremity of a 53-year-old woman cadaver, an unusual high-origin of the pronator teres muscle was discovered. The fibers of the aberrant muscle arose from two bone origins--the medial epicondyle and a small supracondylar process of the humerus, and from a tendinous arch (Struthers' ligament) extending between them. In addition, there was a variation of the musculocutaneous nerve--in the axilary fossa the musculocutaneous was fused to the median nerve and its usual branches arose consecutively from the median nerve stem. The last of these branches--the lateral antebrachial cutaneous arose in the lower part of the arm from the median nerve and companion to it and to the brachial artery passed under the Struthers' ligament. Our findings indicate that in some rare cases of combined muscular-nerve variations, the lateral antebrachial cutaneous nerve can be added to the neurovascular structures possibly entrapped by the Struthers' ligament.